The invention relates to a method of alternately heating and cooling a heat exchanger, such as a press or a reaction vessel, of a heating and cooling apparatus with thermal recovery, in which, during the warm-up phase, the cool liquid returning from the heat exchanger, and during the cool-down-phase, the hot liquid returning from the heat exchanger, is delivered to a reservoir from which, during the warm-up phase, hot liquid is taken for the heater, and in the cool-down phase, cold liquid is taken for the cooler, and in which at least two reservoirs are present, or two sections within one reservoir, into which amounts of liquid of different temperature are delivered from the heat exchanger both during the warm-up phase and during the cool-down phase. The invention furthermore relates to an apparatus for the practice of this method.
A method and an apparatus of this kind have been proposed in copending application Ser. No. 580,700 filed May 27, 1975. They are distinguished from the method disclosed by German Pat. No. 1,113,062 by an improved thermal recovery.
Both in the known method and in the proposed method, at least one reservoir is provided, which, in a certain cycle, is charged one time with hot and another time with cold liquid, or also, in the case of the older patent application, is charged with liquid of medium temperature. In these cases the liquid that is in the reservoir is expelled by a liquid of a different temperature. In this method unavoidable mixing losses occur, which diminish the amount of the possible thermal recovery.
The invention is addressed to the problem of devising a method and an apparatus to make it possible to reduce the percentage of the mixing losses in the overall process. Furthermore, the temperature range which can be economically utilized for the thermal recovery is to be expanded.